Phenol formaldehyde resin

Phenol formaldehyde resins (PF), also called phenolic resins or phenoplasts, are synthetic polymers obtained by the reaction of phenol or substituted phenol with formaldehyde. Used as the basis for Bakelite, PFs were the first commercial synthetic resins. They have been widely used for the production of molded products including billiard balls, laboratory countertops, and as coatings and adhesives. They were at one time the primary material used for the production of circuit boards but have been largely replaced with epoxy resins and fiberglass cloth, as with fire-resistant FR-4 circuit board materials.

There are two main production methods. The acid-catalyzed reaction of phenol and formaldehyde, with the phenol in excess quantity, forms a prepolymer known as novolac which can be moulded and then cured with the addition of more formaldehyde and heat. The other method has instead the formaldehyde in excess and uses a base as catalyst, forming a prepolymer known as resole. There are many variations in both production and input materials that are used to produce a wide variety of resins for special purposes.